clapping sound when lugging the bike?

when i really lug my bike in the bush (low rpm and allot of load) i hear like a clapping sound it started off not too often but now its about half the time when road running.. it sounds like valves or somewhere up in the head (could be anywhere) and the bike starts first kick with the choke on at 0 degrees celsius so im stumped whats going on and can i keep riding?? 

Is it loud like the chain slapping or have you switched chain sliders to a harder one like a T. M. Design works? That is my first thought when reading your post.

my chain is loose but it sounds like something more metalic its hard to explain 

I get this too on my 09. It sounds like something is smacking the front of the motor. Possibly the piston rattling in the cylinder. I have no idea though and would be interested to know what that sound is.

4 stroke motors do make a loud sound when lugged low down. 


Other sounds as mentioned could be the chain on the swingarm guide, also the carb slide plate makes a noise when the bike is a bit older.

Our '09 was having the same sound.  Turned out to be the chain slapping.  I'd start there before worrying too much as it's a simple adjustment that might just solve your problem.

okay thanks guys il let you know how it goes

Sounds a lot like detonation, too lean and lots of carbon on top of the piston.

can cause massive damage.


well just tightened the chain and so far so good noise seems to be gone also would adjusting my fuel screw help me out in colder weather/

I've read that clutches can make a similar chattering noise when you lug the engine around, similar to the chain slap noise. Most bikes seem to make the chain slap noise when set to the factory recommended chain tension when lugging. If getting the noise to go away means taking it out of spec and making it too tight, I wouldn't do it, but if your still within spec... Well no worries then.

If your lugging it to the point it is about to stall the decompression mechanism on the exhaust cam will make a chattering noise. 

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